This invention relates generally to a free-plunging constant velocity universal joint of the tripod type for connecting a first rotatable shaft to a second rotatable shaft which is inclined at a designed joint angle relative to the first shaft. Constant velocity joints of this type are well known and have long been manufactured and sold, for example, by Glaenzer Spicer of Poissy, France.
In general, a free-plunging constant velocity joint of the tripod type comprises an outer housing or tulip-shaped member connected to one of the shafts and formed with three angularly spaced branches which are separated by angularly spaced slots. A tripod is rotatable with the other shaft and is formed with three angularly spaced trunnions which project radially into the slots of the tulip member. A roller is rotatably and slidably supported on each trunnion by an annular row of needles.
Each roller of the tripod is tubular and includes an inner bearing surface and an outer bearing surface. The inner bearing surface of each roller is generally cylindrical and bears against the needles. The outer bearing surface of each roller is spherically shaped and rides against tracks defined by opposing sides of adjacent branches of the tulip member.
The tulip member and the tripod coact to transmit motion between the inclined shafts with constant angular velocity and to allow relative axial movement or plunging of the shafts. As the tripod turns, its rollers slowly rotate about their own axes and oscillate on the tracks of the tulip member. Such oscillation causes the tracks to wear and eventually creates depressions in the tracks. When axial plunging occurs, the rollers roll out of and then back into the depressions and, if the tracks are badly worn so that the depressions are relatively deep, abrupt and unacceptable jerking is produced each time the rollers leave and return to the depressions. Accordingly, track wear is a factor which significantly affects the service life of the joint. The wear is greater when the shafts are inclined at small joint angles than when the shafts are inclined at large joint angles because there is a higher ratio of contact area between the rollers and the tracks at small joint angles.